Temperature responsive switch



Nov. 4; 1941.

M. B. GROUT TEMPERATURE RESPONSIVE swmn Filed Oct. 30, 1959 Mac/Max Mar/m 5 Grow By:

. Zfzey Patented Nov. 4, 1941 TEMPERATURE RESPONSIVE SWITCH Martin B. Grout, Chicago, 111., assignor to Jefferson Electric Company, Bellwood, 111., a corporation of Illinois Application October 30, 1939, Serial No. 301,909

6 Claims.

This invention relates to temperature responsive switches, and more particularly to such switches of the type which are manually set and automatically released.

An object of this invention is to provide a thermostatically controlled switch of the manual reset type which is adapted to the protection of an energy translating device and so constructed that the protective purpose of the switch cannot be defeated by manipulation of the manual resetting element.

Another object of this invention is to provide amanually resettable, trip-free, temperature responsiv'e switch which is inexpensive to build, compact and which breaks a circuit with snap action.

Another object of this invention is to provide a manually resettable, trip-free, temperature responsive switch controlled by a bimetallic element and having an adjustment for controlling the temperature of operation of the switch within limits.

Another object of this invention is to provide a temperature responsive switch including a latch mechanism controlled by a bimetallic element and having the bimetallic element and latch mechanism electrically insulated from the circuit controlling parts of the switch.

Other objects and advantages of this invention will be apparent from the following description and reference to 'the accompanying drawing wherein a preferred embodiment of my invention is clearly described and illustrated.

In the drawing:

Figures 1 and 2 are side elevations of a switch embodying a preferred form of my invention which illustrate different operat ng positions of the switch.

Figure 3 is a side sectional view of the switch shown in Figures 1 and 2 which shows the structural details of the switch.

Figure 4 is a bottom elevation of the switch shown in Figures 1 and 2.

Figure 5 is an exploded view of the parts of the switch shown in Figures 1 and 2.

Figure 6 is a sectional view with the section taken substantially on a line 6-6 of Figure 3 and in the direction of the arrows.

Figure 7 is a fragmentary perspective view of a detail of the switch shown in Figures 1 and 2.

Having particular reference to the drawing, the switch has a base III of insulating material such as molded phenol fiber which is adapted member l5 has a terminal lug I9 thereon projecting outwardly from the end of the base I. Also included in the stack are resilient contact carrying arms 2| and 22 which are separated by an insulating washer 23. The-resilient contact carrying arm 22 has 9. lug 26 thereon for making electrical connections thereto. The stack is held in assembled relation by a screw 24 which. is threaded into an anchor plate 25. The anchor plate 25 is insulated from the contact carrying arm 22 by an insulating washer 21 and the screw 24 is insulated from the conductive members in the stack by tubular insulating member 28. The anchor plate 25 has an inwardly projecting lug 30 thereon.

The contact carrying arms 2| and 22 extend along the surface of the base III in spaced relation thereto and in substantially parallel spaced relation with respect to each other. Contacts 3| and 32 are secured to the extending ends of the contact carrying arms 2| and 22 respectively in alignment for engagement; the contact carrying arms being normally biased to positions such that the contacts are normally separated as shown in Figure 2. The contact carrying arm 2| is preferably somewhat longer than the contact carrying arm 22 and has an opening 33 therein. In the preferred embodiment of my invention, a piece of insulating material 34 is secured to the end of the contact carrying arm 2| adjacent the opening 33 by folding the end of the arm 2| back over the piece of insulating material as at 35. The opening 33 is sufliciently large and the folded portion of the arm is so positioned with respect thereto that the opposite surfaces of the piece of insulating material 34 are exposed through the opening 33.

A yoke 31 is secured to the base |0 near the extending or free end of the contact carrying arm 2| by a rivet 38 or other suitable fastening means. A substantial disc like latch element 39 is rotatably supported by the yoke on a pin or shaft 40 which extends through the latch element and the sides .of the yoke. The latch eleto be secured to a support H such as the cover ment 39 has a recess 4| of such shape that spaced and oppositely projecting integral fingers are provided thereon which fingers engage the exposed opposite surfaces of the insulating piece 34. The ends of the fingers 42 and 43 are preferably rounded and so spaced that the movements of the latch element and contact carrying arm are dependent, and there is only a small surface of engagement between the ends of the fingers 42 and 43 and the insulating piece 34.

A substantial V-shaped temperature responsive bimetallic element 45 has the spaced ends at the open end of the V secured to the base I adjacent the stack l4 by ends of the angular conductive members 4 and i which extend therethrough and are swedged or riveted as at 46 and 41. The closed end of the V-shaped bimetallic element is adapted to engage a shoulder 48 on the latch element 39 to hold the resilient contact carrying arm 2| in a position such that the contacts 3| and 32 are biased into engagement, as shown in Figure 3. An adjusting screw 49 extends between the legs of the bimetallic element and is threaded into the lug 30 on the anchor plate 25. Washers '50 and 5| are provided adjacent the head of the screw 49; the washer 50 engaging the legs of the bimetallic element to effect adjustment of the normal position of the extending end of the bimetallic element upon adjustment of the screw 49.

A manually operable actuating member 52 is slidably mounted in an opening 53 in the base It] and has a projecting end portion 54 which extends through an opening 6| in the contact carrying arm 2| and engages the surface of the contact carrying arm 22. The opening 6| is sufficiently large that the contact carrying arm 2| is freely movable along the projecting end portion 54. The contact carrying arm 2| engages the surface of a shoulder 55 on the actuating member when pressure is applied to that actuating member and the projecting end portion 54 is sufiiciently long that the contact carrying arms 2| and 22 are held apart and the contacts 3| and 32 are separated while sufficient force is applied to the actuating member to overcome the normal biasing force of the contact carrying arm 22. A rim or collar 56 is preferably integral with the actuating member 52 and is disposed between the surface of the base l0 and a cupshaped cap to prevent excessive movement of the actuating member in either direction with respect to the base. An exposed or operating por tion of the actuating member 52 projects outwardly through an opening 58 in the cap 51. The cap 51 is located with respect to the base by an integral collar 59 and is preferably provided with a flange 60 which is clamped between the base Hi and the surface of the support II to which the switch is secured. The switch is preferably secured in position with respect to the support H by one or more screws such as 62 which are threaded into bushings such as 63, which bushings are preferably molded into the base It].

In the operation of the switch disclosed, the resilient contact carrying arms 2| and 22 are normally biased to positions such that the contacts 3| and 32 are separated. This normal position of the contact carrying arms and the corresponding position of the actuating member is illustrated in Figure 2. When pressure is applied to the actuating member 52, the end surface of the end portion 54 engages the contact carrying arm 22 and the surface of the shoulder 55 engages the contact carrying arm 2| to move the contact carrying arms against their normal biasing forces to positions such as those illustrated at 2|a, 22a and 52a in Figure 1. Since the latch element 39 rotates to follow the movement of the contact carrying arm 2|, the shoulder 49 moves to a position such as that illustrated at 43a. During such movement, and when such pressure is applied to the actuating element 52, the contacts 3| and 32 are held apart. Upon release of the pressure applied to the actuating element 52, the latch element 39 forces the return movement of the contact carrying arm 2| effected by the normal biasing force of that arm until the shoulder 48 engages the end of the bimetallic element to be stopped and held thereby. After such engagement of the latch element and bimetallic element the contact carrying arm 2| is held by the latch element 39 in a position such as that illustrated at 2|b in Figure 1, and the continued release of pressure on the actuating element permits the contact carrying arm 22 to move to the position in which the contacts are closed, which position is indicated at 221) in Figure 1. If the bimetallic element is in an abnormal position or for any reason fails to engage the latch element 35, the contacts remain separated and return to their normal position which is indicated in Figure 2 when the pressure is released from the actuating member 52.

When the latch element is engaged by the bimetallic element in the normal operation of the switch, heating of the bimetallic element which produces sufficient flexure thereof releases the latching element 39 and the resilient contact carrying arms return to their normal positions in which the contacts are separated. The operation of the contacts occurs with a snap action during the movement of the resilient contact carrying arms which forces the release of the latch element. When pressure is applied to the actuating member, which is sufficient to overcome the biasing force of the contact carrying arm 22 or both contact carrying arms, the contacts are held apart. When pressure is released from the actuating member and the latching element secures the position of the contact carrying arm 2| so that engagement of the contacts is effected, there is suflicientspacebetween the shoulder and the contact carrying arm 2| to permit sufficient movement of the contact carrying arm 2| upon release of the latch element 39 to effect separation of the contacts. It is therefore apparent that the purposes of the switch cannot be defeated by securing the actuating member 52 in any position.

While the embodiment of the present invention which is herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all of which come within the scope of the claims which follow.

What is claimed is:

1. A trip-free temperature responsive switch comprising, in combination, a base, a pair of resilient arms having adjacent ends anchored to the base and extending in the same direction, contacts secured to the arms in alignment for engagement, said arms normally biasing the contacts to disengaged positions, a manually operable actuating member having separate surfaces engaging the arms and adapted to hold the arms in spaced relation with the contacts disengaged until manual force upon said member is released, a bimetallic strip temperature responsive element having an end anchored adjacent the anchored ends of said resilient arms, and a latch engaged by the temperature responsive element for holding the contacts in engagement until released by the temperature responsive element after manual force is released from the actuating member, said latch including a disc rotatably secured to the base near the free end of one of said resilient arms, said disc being operatively connected to the said one of the resilient arms so that the positions of the disc and arm are dependent.

2. A trip-free temperature responsive switch comprising, in combination, a base, a pair of resilient arms having adjacent ends anchored to the base and extending in the same direction, contacts secured to the arms in alignment for engagement, said arms normally biasing the contacts to disengaged positions, a manually operable actuating member having separate surfaces engaging the arms and adapted to hold the arms in spaced relation with the contacts disengaged until manual force upon said member is released, a temperature responsive element comprising a bimetallic strip having an end anchored adjacent the anchored ends of said resilient arms, and a latch engaged by the temperature responsive element for holding the contacts in engagement until released by the temperature responsive element after manual force is released from the actuating member, said latch including a disc rotatably secured to the base near the free end of one of said resilient arms, said disc having integral fingers engaging opposite sides of said one of the resilient arms to provide a movable connection between the disc and arm.

3. A trip-free temperature responsive switch comprising, in combination, a base, a pair of resilient arms having adjacent ends anchored to the base and extending in the same direction, contacts secured to the arms in alignment for engagement, said arms normally biasing the contacts to disengaged positions, a manually operable actuating member having separate surfaces engaging the arms and adapted to hold-the arms in spaced relation with the contacts disengaged until manual force upon said member is released,

a temperature responsive element having an end anchored adjacent the anchored ends of said resilient arms, means for adjustably varying the normal position of the temperature responsive element, and a latch engaged by the temperature responsive element for holding the contacts in engagement until released by the temperature responsive element after manual force is released from the actuating member, said latch including a disc rotatably secured to the base near the free end of one of said resilient arms, means providing a movable connection between the disc and the said one of the resilient arms.

4. In a switch, the combination comprising adjacent control carrying arms having contacts mounted thereon in alignment for engagement,

said arms being normally biased to positions such that the contacts are disengaged, insulating means secured to the end of one of the arms, latch means adapted to engage opposite sides of the insulating means and movable responsive to movements of said one of the arms in either of the opposite directions of movement thereof, and means holding the latch means in a position such that the contacts are biased into engagement.

5. In a switch, the combination comprising adjacent contact carrying arms having contacts mounted thereon in alignment for engagement, said arms being normally biased to positions such that the contacts are disengaged, insulating means secured to the end of one of the arms, a rotatably mounted member having fingers engaging opposite sides of the insulating means, said rotatably mounted member being rotated by movements of said one of the arms in either of its directions of movement, and a bimetallic temperature responsive element having one end anchored and the other end engaging the rotatably mounted member to hold the rotatably mounted member in a position such that the contacts are biased into engagement.

6. A trip-free temperature responsive switch comprising in combination a base of insulating material having spaced parallel projections at one end thereof and latch means rotatably supported at the other end thereof, a stack including a pair of support brackets, a pair of contact carrying springs and insulating meanssecured to the base between said projections, said contact carrying springs having cooperating contacts mounted thereon and normally biased to positions in which the contacts are separated, said latch means including means adapted to engage opposite sides of one of the contact carrying springs so as to be movable therewith, a temperature responsive bimetallic element secured to said support brackets and extending to a position such that it engages the latch means to hold the contact carrying springs in positions such that the contacts are engaged, and manually operable means having separate surfaces adapted to engage the contact carrying springs for effecting operation of the contact carrying springs and latch to positions of contact engagement.

MARTIN B. GROUT. 

